Indoor Air Quality
People spend most of their time indoors, and indoor air can be more polluted than outdoor air. Some pollutants cause headaches and allergies; others, like radon and carbon monoxide, can be deadly. Most problems can be fixed by controlling the source, ventilating and filtering.
- Homeowners
- Tenants
Common indoor pollutants
| Pollutant | Sources | What to do |
|---|---|---|
| Carbon monoxide | Furnaces, water heaters, gas stoves, generators, cars in garages | CO alarms, yearly appliance checks, never run engines indoors. See Smoke & CO Alarms |
| Radon | Soil under the house | Test; fix high levels. See Radon |
| Mold and moisture | Leaks, high humidity, poor bathroom ventilation | Fix leaks, keep humidity between about 30% and 50%. See Mold at Home |
| VOCs (chemical vapors) | Paints, cleaners, glues, new furniture and flooring, air fresheners | Choose low-VOC products, ventilate, store chemicals outside living areas |
| Combustion particles | Wood stoves, fireplaces, candles, gas cooking, tobacco smoke | Use range hoods, keep stoves maintained, don’t smoke indoors |
| Dust and allergens | Pets, dust mites, pollen | Vacuum with a HEPA vacuum, wash bedding hot, use good filters |
| Lead and asbestos dust | Renovating older homes | Test first, contain the work. See Lead & Asbestos |
Three ways to improve indoor air
- Control the source: remove or reduce what’s polluting the air. This works best.
- Ventilate: use bathroom and kitchen exhaust fans that vent outside, and open windows when outdoor air is clean.
- Filter: use a MERV 13 or higher filter in your HVAC system if it can handle it, and portable HEPA air cleaners sized for the room.
Smoky days
During wildfire smoke events, keep windows closed, run filtration, and avoid adding indoor smoke from candles and frying. A box fan with a MERV 13 filter taped to it can be a low-cost air cleaner (follow safety guidance and don’t leave it unattended). See Wildfire Smoke.
Quick check
- CO alarms on every level and outside sleeping areas
- Radon tested in the last few years
- HVAC filter changed on schedule
- Bath and kitchen fans vent outdoors and get used
- No visible mold or musty smells
- Chemicals and fuels stored outside the living space
Avoid ozone generators sold as air purifiers. Ozone irritates the lungs, and these devices don’t remove most pollutants.
Standards & references
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